Page:Scientific results HMS Challenger vol 18 part 2.djvu/501

Rh parallel and vertical, but more or less divergent. Length of the three joints = 1 : 2 : 8, breadth = 1 : 2 : 4. Whole shell slender, pyramidal. Mouth square, four-lobed.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.24; breadth, a 0.03, b 0.06, c 0.12.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

3. Cycladophora lanterna, n. sp.

Shell very similar to the two preceding species, but differing in the following characters. Cephalis subspherical, with a thick, pyramidal horn of the same breadth, and three times the length. Thorax hemispherical, with circular, hexagonally-framed pores. Abdomen ovate, with four convex ribs, and twelve large holes, four superior smaller pentagonal, four intermediate very large, ovate, and four inferior, small, triangular holes. Mouth little constricted, nearly circular.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.22; breadth, a 0.025, b 0.08, c 0.11.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Definition.—Abdomen with six radial ribs (three primary or perradial, and three alternate, secondary or interradial).

4. Cycladophora hexapleura, n. sp.

Lanterna chinensis, Bury, 1862, Polycystins of Barbados, pl. xiii. fig. 7.

Shell shaped like a lantern, with six sides and two sharp strictures. Length of the three joints = 1 : 2 : 8, breadth = 1 : 2 : 4. Cephalis hemispherical, with a conical spine of the same length. Thorax twice as large, hemispherical, with regular, circular pores. Abdomen nearly six-sided prismatic, with six descending, little curved ribs, and eighteen large holes between them; six superior holes interradial, ovate, six intermediate holes very large, perradial, ovate, six inferior holes triangular, interradial. Mouth six-lobed.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.16; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

5. Cycladophora pyramidalis, n. sp.

Podocyrtis sp., Bury, 1862, Polycystins of Barbados, pl. xii. fig. 2.

Shell slender, pyramidal, with six sides and two slight strictures. Length of the three joints = 1 : 4 : 12, breadth = 1 : 4 : 8. Cephalis subspherical, with a conical horn of twice the length. Thorax conical, with regular, circular pores. Abdomen truncate, pyramidal, with six strong, divergent, straight ribs, which are connected by five to six transverse, hexagonal rings; therefore